Method and apparatus for generating sonic signals



Sept. 17, 1968 s, RODBELL 3,402,386

METHOD AND APPARATUS FOR GENERATING SONIC SIGNALS Filed Dec. 26, 1963 TA v V IL I I Volume 5 1 I Time Fig. 3.

Magnet/c Pie/d 7'lme Fig. 4. P 3 N F" A a Pressure Time 30 lm/enforDana/O'SROO'b,

by 7M 35$? 3,402,386 METHOD AND APPARATUS FOR GENERATING SONIC SIGNALSDonald S. Rodbell, Burnt Hills, N.Y., assignor to General ElectricCompany, a corporation of New York Filed Dec. 26, 1963, Ser. No. 333,6024 Claims. (Cl. 340-12) The present invention relates generally to theart of sonic signal generation and is more particularly concerned with anovel method of producing sonic signals and with unique apparatusimplementing that method.

There has been a long-standing, generally recognized need for a methodor means by which sonic signals could be produced over a broad frequencyrange in a variety of media. Sonic signals in useful frequency rangescan be generated by mechanical motion, as by a motor-driven piston, orby magnetostrictive or electrostrictive effects. Sonic impulses can alsobe produced by crystallographic conversions where these involve volumechanges but for a variety of reasons, sonic signal generators,particularly sonar projectors, employ the dimensional linear changeprinciple instead of volume expansion which might offer specialadvantages, particularly in very deep water applications.

The depth limitation and other shortcomings of modern sonic signalingequipment have long been recognized and have resulted in sustainedresearch and development efforts. However, prior to the inventiondisclosed and claimed in the copending application filed of even dateherewith in the names of Donald S. Rodbell, Ralph W. De Blois and PhilipE. Lawrence, Ser. No. 333,600, filed Dec. 26, 1963, now abandoned, andassigned to the assignee hereof (the entire disclosure which isincorporated herein by reference), these efforts did not result in anybreakthrough advance. Rather, the development of sonar projectionequipment prior to that invention was confined to incrementalimprovements in apparatus operating on the principle of singledimensional linear change.

The present invention affords a new and effective way of using the basicconcept of the aforesaid invention and in doing so may employ in aspecial form the invention disclosed and claimed in the copendingapplication filed of even date herewith in the names of Donald S.Rodbell, Ralph W. De Blois, Ser. No. 333,601, filed Dec. 26, 1963, nowabandoned, and Ronald H. Wilson and likewise assigned to the assigneehereof (the entire disclosure which is also incorporated herein byreference). Thus, in accordance with the present invention, a body offirst-order phase transformation material such as a manganese arseniderod may be caused to produce sonic signal pulses at double the inputsignal frequency without any increase in electrical power requirements.Furthermore, this result can be obtained without any significantoffsetting disadvantage such as a reduction in the operating frequencyrange or diminished signal strength. In fact, at higher frequencies ofthe order of hundreds of cycles per second and higher, an additionaladvantage may be realized in that the latent heat involved in transitionfrom one state to the other may be used as a flywheel since the energyinvolved is not dissipated to a significant extent during each cycle.

Basically, this invention involves repeatedly switching a body offirst-order phase transformation material from its collapsed state toits expanded state and back again through the use of a magnetic pulseand a pressure pulse or sonic shock wave applied alternately to thebody. Thus, in method terms, this invention broadly defined comprisesthe steps of causing the manganese arsenide or similar body in itscollapsed state to undergo a firstorder phase transformation and therebyproduce a shock nited States Patent wave and then subjecting the body toa sonic shock wave and thereby causing the body to undergo anotherfirstorder phase transformation and produce a second shock wave inreturning to its initial collapsed state. In actual use, this methodpreferably involves the frequent repetition of this cycle of expansionand contraction and there will be a predetermined interval between eachfirst-order phase transformation which may be adjusted through apparatusdesign and in other ways, as will subsequently be described in detail.Also preferably, for certain purposes the resetting or collapsing actionwill in accordance with this invention be applied or implemented by anecho portion of the sonic shock wave produced by the magnetic pulse andthe initial first-order phase transformation of each cycle resultingtherefrom. Alternatively, it may be desirable in some instances due toecho attenuation or for some other reason to use some other pressurepulse source such as another sonic shock wave produced by theapplication of a magnetic pulse to a second manganese arsenide body orthe like.

In its apparatus aspect, this invention generally described comprises abody of material having a firstorder phase transformation characteristicand having an annular side surface portion, a closed vessel containingthis body and having an inner annular wall surface portion and a sonicsignal-transmitting fluid in the vessel and surrounding and contactingthe body and filling the space between the body and the opposing vesselwall surface. The body is disposed in the vessel with its annularsurface portion substantially equidistantly spaced from the innerannular opposed surface portion of the vessel and a magnetic pulsesource means is provided for subjecting this body to magnetic fieldpulses causing it to undergo a first-order phase transformation andthereby produce shock waves in the fluid contained in the vessel. Whileit will be understood that within this general definition a variety ofshapes of bodies and vessels may be used, it is my preference to employa rod-like body and to use a steel cylinder with the body disposedcoaxially therein. It is further my preference to provide a liquid inthe cylinder to transmit sonic shock waves from the body to the cylinderand back to the body for the purpose of resetting it. The magnetic pulsesource means is preferably an insulated coil which is disposed aroundthe body for maximum effect.

Those skilled in the art will gain a further and better understanding ofthis invention from the detailed description set out below, referencebeing had to the drawings accompanying and forming a part of thisspecification, in which:

FIG. 1 is a transverse sectional, partially diagrammatic view ofapparatus incorporating this invention, including sonic signalgenerating means and signal read-out means;

FIG. 2 is a chart on which volume is plotted against time to illustratethe volume changes accompanying firstorder phase transformations in thecourse of signal generation in accordance with this invention;

FIG. 3 is another chart on which magnetic field is plotted against time,showing the effect of magnetic field pulses in producing first-orderphase transformations and the resulting sonic signal shock waves;

FIG. 4 is still another chart on which pressure is plotted against time,the resulting curve indicating the incidence of the pressure pulses andtheir location in time relative to the magnetic field pulses and thevolume changes of FIGS. 2 and 3; and

FIG. 5 is a view similar to FIG. 1 of apparatus embodying another formof the present invention.

With reference to FIG. 1, tank 10' containing a body of water 11 isequipped with sonic signal sensing readout means 13 exposed below thesurface of the water body 11 and including a barium titanate transducerelement indicated at 14 and leads 15 and 16 connecting element 14operatively to a suitable read-out device 17. A closed cylidrical vessel20 is disposed in tank 13 below the surface of water body 11 and isfilled with a body of transformer oil 21. A solid cylindrical rod-likebody of manganese arsenide 22 is disposed in vessel 20' and supported bysuitable bracket means (not shown) coaxially of vessel 20. A magneticcoil or solenoid 24 is disposed around rod 22 an is connected by leads25 and 26 to a current pulse source whereby magnetic field pulses ofsuflicient magnitude are generated and under the conditions of operationof the device cause switching of the manganese arsenide rod 22.

In the operation of the device of FIG. 1, rod 22 is initially in itscollapsed state. This is indicated in FIG. 2. by the V symbol at itspoint of origin at zero time. After a brief interval of time, coil 24 isenergized by a current pulse either through manually or automaticallyoperated pulsing means as indicated by curve M of FIG. 3. As indicatedabove, the magnetic field resulting causes rod 22 to undergo afirst-order phase transformation and to increase in volume producing ashock wave designated at T of FIG. 4 by the peak P The magnetic field isdiscontinued as the current pulse terminates but the rod 22 remains inits expanded state until an echo of the initial shock wave in liquid 21returns from the cylindrical side wall of vessel 20. This occurs at timeT as indicated by peak P of FIG. 4 and results in return of rod 22 toits collapsed state via a first-order phase transformation. Then again,after an interval of time represented by the spacing of T and T of FIG.2, a magnetic field pulse is again applied to rod 22, as indicated inFIG. 3, transforming it once again to its expanded state and producinganother shock wave in liquid body 21 indicated by the peak P of FIG. 4.

The stock waves produced by thus switching manganese arsenide body 22from its collapsed to its expanded state are transmitted in part byvessel 20 to the surrounding water body 11 and are detected and read outthrough a detection apparatus 13. Vessel 20, thus, is of metalconstruction and has a relatively thin wall for effective sonic signaltransmission to the surrounding medium. This vessel side wall, however,is effective also to reflect or echo a portion of the initial shock waveto reset manganese arsenide rod 22.

In the apparatus illustrated in FIG. 5, a tank 30, like tank 10, isprovided as the container for the test apparatus and is nearly filledwith a body of water 31. Again, sonic signal detection and read-outapparatus 33 is provided, including a barium titanate transducer sensingelement 34 which is connected by leads 35 and 36 to a suitableconventional sonic signal read-out mechanism 37 disposed outside vessel30.

Sonic signal generation apparatus of FIG. 5 comprises a dumbbell-shapemetal vessel 40 providing two generally cylindrical chambers 41 and 42,communicating through a central passageway 43. The chambers andpassageway of vessel 40 are filled completely with transformer oil body44. A solid cylindrical body 46 of manganese arsenide-composite materialis centered in chamber 41. Body 46 is of the type described in Example Iof my copending application filed of even date herewith, and entitled,Composite Articles for Generating Sonic Signals and Method, Ser. No.333,603, filed Dec. 26, 1963, now abandoned, and assigned to theassignee hereof, the entire disclosure of which is incorporated hereinby reference. A similar manganese arsenide composite body 47 issimilarly situated in chamber or compartment 42. S01- enoids 49 and 50are disposed, respectively, around composite bodies 46 and 47 and areconnected to current pulse sources (not shown) outside vessel 40 andtank 30 by means of leads 52 and 53 (for coil 49) and leads 54 and 55.

In the operation of the FIG. 5 apparatus, a sonic shock wave or signalfrom one composite first-order phase transformation body is used insteadof an echo to switch the other body. Accordingly, the walls of vessel 40may be substantially lighter and thinner than the side wall of vessel 20to maximize sonic signal transmission into water body 31. Therefore, itwill be understood that the operation of this apparatus involvesalternately subjecting composite bodies 46 and 47 to magnetic fieldpulses to produce a first-order phase transformation and accompanyingsonic shock wave in fluid 44 and also to thereby reset or collapse theother composite body in preparation for the next firing of it by amagnetic field pulse.

The frequency of oscillation of the devices described above may beselected on the basis of the dimensions of the vessel, that is, thedistance between the point of origin of the resetting pressure pulse andthe first-order phase transformation body to be reset thereby. In thecase of FIG. 1, the sonic velocity of the signal in the liquids bodytaken together with the distance that the signal must travel initiallyand that the echo must return, fix the time between actuation and reset.Thus, the pressure wave produced on actuation initially travels awayfrom the manganese arsenide body and in part is reflected back upon thatbody. But whether this apparatus or that of FIG. 5 or something else isused in carrying out this new method, the frequency of operation ofthese devices may vary over a wide range of preference although it willgenerally be desirable that the sequences be performed at hundreds ofcycles per second and higher. An advantage in this practice is that thelatent heat evolved in the transformations will not to any materialextent be diffused away between switching operations, even under themost favorable heat-exchange circumstances.

It will be further understood that the apparatus of FIG. 1 and that ofFIG. 5, another apparatus within the purview of this invention, may beoperated in other environments than that provided by tanks 10 and 30.Thus, where the purpose is ranging or signaling purposes in large bodiesof water, these tanks would not be used and the sonic signal might begenerated at great depths and read out at such depths or near thesurface by suitable conventional sonic signal detection means.

The following illustrative, but not limiting, examples of this inventionas it may advantageously be carried out are offered to further informthose skilled in the art of the specific nature of the method andapparatus of this invention:

Example I A composite rod produced in accordance with Example I of myaforesaid copending application, entitled Composite Articles forGenerating Sonic Signals and Method, is used as a shock wave or signalsource. This rod, onesixteenth inch in diameter and four inches long isenclosed in a stainless steel cylinder eight inches long and held inplace coaxially and longitudinally centered in the cylinder by means ofspring clips secured to the cylinder end walls. The end walls and theside wall of the cylinder are of 16-gauge thickness and the cylinder isfilled with transformer oil and sealed against leakage. This rod andcylinder assembly is disposed in a test vessel containing 50 gallons ofwater, with the stainless steel cylinder be ing disposed below the topsurface of the water, and the rod is then subjected to magnetic fieldpulses by means of a solenoid coil disposed around the rod and connectedto an electric power source outside the vessel, as indicated in FIG. 1of the drawings accompanying this specification. The current pulsespowering the coil are delivered at an appropriate frequency and theresulting sonic signals produced in the transformer fluid andtransmitted to the surrounding test vat water body are detected and readout by a standard barium titanate transducer element and systempresently in general use in under-Water signaling operations. Sonicsignals are produced each time the coil is energized and at intervalsimmediately following, in-

dicating the resetting action of a pressure pulse or echo reflected bythe vessel side wall.

Having thus described this invention in such full, clear, concise andexact terms as to enable any person skilled in the art to which itappertains to make and use the same, and having set forth the best modecontemplated of carrying out this invention, I state that the subjectmatter which I regard as being my invention is particularly pointed outand distinctly claimed in what is claimed, it being understood thatequivalents or modifications of, or substitutions for, part of thespecifically described embodiments of the invention may be made withoutdeparting from the scope of the invention as set forth in what isclaimed.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Apparatus for continuous cyclic generation of sonic signalscomprising a body of material characterized by having a magneticfirst-order phase transformation, a closed vessel enclosing the body andproviding a space between said body and a wall of the vessel, a sonicshocktransmitting fluid in the vessel filling space between the saidbody and a wall of the vessel, magnetic field source means operativelyassociated with the body and the vessel to subject the said body tomagnetic field pulses in predetermined sequence and thereby cause abruptchanges in the specific volume of the body of at least 0.01 percent atpredetermined intervals, and resetting means in the vessel and spacedfrom said body for generating sonic shock waves in the sonicshock-transmitting fluid to reset the said body after each actuation ofthe magnetic field source means.

2. The method of generating sonic signals which comprises the steps ofsubjecting a body of material having a first-order phase transformationcharacteristic in its collapsed state to a magnetic pulse of shortduration and thereby causing the body to undergo a first-order phasetransformation and produce a shock wave, then subjecting the said bodyto a pressure pulse and thereby causnig the body to undergo anotherfirst-order phase transformation and produce a second shock wave inreturning to its collapsed state, and repeating the cycle to produce aseries of sonic signals in predetermined pattern.

3. The method of generating sonic signals which comprises the steps ofsubjecting a manganese arsenide body in its collapsed state to a seriesof short-duration magnetic pulses and thereby causing the body toundergo a corresponding series of first-order phase transformations andproduce a corresponding series of shock waves, and subjecting the saidbody to a series of pressure pulses alternating with the magnetic pulsesand thereby causing the body to undergo another series of first-orderphase transformations and produce a second series of shock Waves inreturning to its collapsed state.

4. The method of generating sonic signals which comprises the steps ofsubjecting a manganese arsenide body in its collapsed state to amagnetic pulse of short duration and thereby causing the body to undergoa first-order phase transformation and produce a shock wave, then aftera predetermined interval subjecting the said body to an echo of theshock wave and thereby causing the body to undergo another first-orderphase transformation and produce a second shock wave in returning to itscollapsed state, and then after another predetermined interval againsubjecting the said body to a magnetic pulse of short duration andthereby causing the body to undergo another first-order phasetransformation and produce a third shock wave, and then again resettingthe manganese arsenide body to its collapsed state by subjecting saidbody to an echo of the third shock wave.

References Cited UNITED STATES PATENTS 2,728,901 11/1952 Millen 340-8 X3,126,347 3/1964 Swoboda 252--62.5 3,140,942 7/1964 Walter -122 RODNEYD. BENNETT, Primary Examiner.

J. P. MORRIS, Assistant Examiner,

1. APPARATUS FOR CONTINUOUS CYCLIC GENERATION OF SONIC SIGNALSCOMPRISING A BODY OF MATERIAL CHARACTERIZED BY HAVING A MAGNETICFIRST-ORDER PHASE TRANSFORMATION, A CLOSED VESSEL ENCLOSING THE BODY ANDPROVIDING A SPACE BETWEEN SAID BODY AND A WALL OF THE VESSEL, A SONICSHOCKTRANSMITTING FLUID IN THE VESSEL FILLING SPACE BETWEEN THE SAIDBODY AND A WALL OF THE VESSEL, MAGNETIC FIELD SOURCE MEANS OPERATIVELYASSOCIATED WITH THE BODY AND THE VESSEL TO SUBJECT THE SAID BODY TOMAGNETIC FIELD PULSES IN PREDETERMINED SEQUENCE AND THEREBY CAUSE ABRUPTCHANGES IN THE SPECIFIC VOLUME OF THE BODY OF AT LEAST 0.01 PERCENT ATPREDETERMINED INTERVALS, AND RESETTING MEANS IN THE VESSEL AND SPACEDFROM SAID BODY FOR GENERATING SONIC SHOCK WAVES IN THE SONICSHOCK-TRANSMITTING FLUID TO RESET THE SAID BODY AFTER EACH ACTUATION OFTHE MAGNETIC FIELD SOURCE MEANS.